v8 XC90. After a leak in sunroof, I noticed water coming down front pillar-driver's side. This is the first time it's leaked and could have been the way I was parked. About 3 days later it wouldn't start after sitting about 2 hours. Gave "brake sensor, start prevented try again", message. The alternator was replaced 8/2014. I replaced the battery because of this issue. Helped for about 10 starts and I though it was fixed, then issue reappeared. It either immobilizes and gives the above messages, or if I disconnect battery for a few minutes it will try to start and act like it is trying to prevent the starting. I pulled the CEM since that's what a lot of folks said and it was clean and dry, no signs of water. I'm at a loss here and really need a car. It has ~130k on it, but it's been a good car other than this.
blocked sunroof drain sounds like the water issue .Take of the a pillar and see if there is a large connector there check for corrosion .As for no start have you tried both keys ,also could just be bad antenna ring where the key goes in ..hope this helps